Radio transmitting-receiving circuit



t. l5, 1935. w. c. HILL RADIO TRANSMITTING RECEIVING CIRCUIT Filed March 23, 1952 Inventor Patented Oct. 15, 1935 UNITED STATES OFFICE RADIO TRANSM'ITTING-RECEIVING CIRCUIT 9 Claims.

My invention relates tov radio circuits, and par'- ticularly to a combination radio transmittingreceiving circuit.

It is an important object of my invention to provide a radio circuit of this type adapted to be utilized, for instance, in each of a plurality of related stations for intercommunication, which plurality of stations is tuned to a standard frequency transmitter or master station.

It is also an important object of my invention to provide dependable means of intercommunication between stations related in a radio circuit and to make practical the application of commercial telegraph printers to radio circuits.

It is also an important object of my invention to utilize in a circuit of the type described the regenerative principle, and to dispense with the usual detector circuits.

Other objects and advantages of my invention Will be apparent from a reading of the following description in connection with the "drawing, wherein for purposes of illustration I have shown a preferred embodiment o-f the invention.

In the drawing:-

The single gure isV a general diagrammatic View of a circuit embodying the principles of my invention. y

Though the use of tuned regenerative receivers for communication purposes is not entirely new, instances are known when communication was had between a plurality of stations having regenerative receivers which were tuned to one frequency and intercommunication carried on by using the oscillation test buttons for keying. InstancesV are also known wherein aro transmitters were keyed by employing an inductiveloop next to the antenna inductance, the keying effect being produced by varying the induotance of the circuit by closing the loop, thereby changing the requency. In' these as in my invention it appears essential t'hat the keying impulses vary the frequency of the regenerative circuit about at least one kilocycle, in order to provide the necessary audio note at all of the related stations.

The device of my invention is intended to provide a dependable means of intercommunication between stations related in a radio circuit, the stations utilizing commercial. telegraph printers. It is-beleved to be clear that none of the elements in my circuit explained below is restricted inv use to the circuit of the invention, but they may be used in other circuits for other uses, as may the main circuit or device of the invention.

Referring in detail to the drawing, wherein like numerals refer to like parts throughout (Cl. Z-13) the same, the numeral 5 refers to the antenna and the numeral 6 to the ground, comprising the antenna and ground system of my circuit, and this feeds the power regenerative receiving circuit generally designated by `5. the numeral 1. This power regenerative receiving circuit not being preceded by radio frequency stages, will reradiate energy into the antenna when it is caused to oscillate. By providing this power regenerative receiving circuit l0 so as to tune broadly, it is an easy matter to cause it to oscillate at the frequency of the standard frequency transmitter, not shown in the drawing. By this means, all ofthe transreceiver circuits in the related series of stations 15 will be similarly tuned, and all will be thereby caused to oscillate at exactly the same frequency.

It will be pointed out herein how small deviations from the standard frequency, which are liable to occur in the oscillating circuits, will not 2.0 interfere with the purposes of my invention.

Because of the phase relationships of the carrier currents transmitted from each station, they will affect each other in such a way as to increase or decrease the total vector sum of the current at each station. Thus, when one power regenerative receiving circuit is keyed so as to vary the amplitude and frequency of the current radiated by this circuit, an aural effect corresponding to this keying will be produced at all of the related stations. The keying may be e1'- fected in this circuit by employing a loop, inductively coupled to the oscillating circuit, designed so that it will change the oscillating frequency of the circuit approximately one kilocycle when it is keyed. A conventional type of audio frequency generator keys this loop at an audio frequency number of times a second when the transmitting key is closed. All stations in the related circuit will utilize the same audio frequency.

By further reference to the drawing, it will be noted that the power regenerative receiving circuit l! feeds an audio frequency amplier circuit generally designated by the numeral 8, which in turn feeds the radio -toning device which is covered by my U. S. Patent No. 1,868,357. The radio toning device or other suitable circuit is arranged so as to be capable of being tuned so as to emphasize the keying audio frequency modulations, and to suppress other undesired impulses. The radio toning device is tuned to pass through the frequency of the intelligence audio frequency modulation, but effectively reject all other audio frequency impulses. The radio toning device also serves as a volume cushion, tending to smooth out the amplitudes of the intelligence impulse frequency, originating either at the local station or at other stations.

It Will be seen by further reference to the drawing that the radio toning device 9 feeds the audio frequency amplifier I2, being connected through a battery Ill directly to the grid of the amplifier tube I I, the output of this tube being fed to a tuned audio frequency transformer I2,

which is tuned to the modulation frequency. The modulation frequencies or audio impulses are amplified in the audio frequency amplifier circuit I2a. Monitoring phones I3 are connected to the output of the audio frequency amplifier I2. A diaphragm coil microphonic device such as a headphone may be used in the radio toning device. It is desired to emphasize that the radio toning device, and its associated amplifier circuits, can be used to advantage in other circuits not identied with the device of the invention described herein; Connected to the output of the audio frequency amplifier I2a is the rectifier I4, which rectiiies the intelligence impulses so as to render them capable of actuating the printer receiving relay, the printer being generally designated by the numeral I5. The printer sending or transmitting relay iii, which may be substituted by the manual keying relay generally designated I1 is connected to the audio frequency generator keying system generally designated by the numeral I 8, whereby to cause the audio frequency modulation generator to send current into the keying loop.

It will now be understood that the tube 28 oscillates continuously during both the transmitting and the receiving periods by virtue of the regenerative feedback 1. During receiving periods these oscillations beat, at a tone frequency with the received interrupted continuous-waves collected on the antenna 5. Telegraphic tone signals result through the output 1a, which are impressed on the audioamplifying apparatus 8, 9, I0, II, and I2a, and are recorded at I3 and/or I5. To transmit signals a keyed tone frequency from source I8 is impressed through the coil 29 onto the high frequency 4Wave generated in the oscillator-detector 28. The resulting modulated high frequency is radiated and received at a distant station which includes an oscillator-detector constructed and tuned like that already described and shown.

The connections between the elements described above may be conventional, and accordingly such connections are not described, lest they be construed as limitations upon the invention.

The said radio toning device, shown and devscribed in my said Letters Patent No. 1,868,357 issued to me on July 19, 1932, makes possible the adaptation of the intelligence signals for acoustical and automatic typing machine reception in a multiple station system of the type indicated by 'being unaffected by any frequency except the modulation frequency, and by avoiding the effectsof the presence of different receiver oscillation frequencies and converting all sounds to a single pleasing note. In so doing the device eliminates interference noises, such as static and key clicks, the elimination of Which is required for automatic Vtyping machine reception. Electrical filtering devices have not proved successful for eliminating interference and static, but may be used with good effect when placed in the ampli- ,fier portion` of circuits such as those described herein supplemented by the radio toning device.

Z5 in the side of the resonance tube 24 against the diaphragm of the microphone 26. The primary form of the vibrations in each of the resonance tubes may be modified by means of the adjustable pistons 2| and 2'I, respectively, so as to control the effect upon the diaphragm of the microphone and thereby condition the operation of the amplifier tube I I and hence the tuned audio transformer and audio frequency amplifier units in the desired manner.

Though I have shown and described herein a preferred embodiment of the invention, it is to be definitely understood that I do not desire to limit the application of this invention thereto, and any change or changes may be made in structure and arrangement of parts Within the spirit of the invention and the scope of the subjoined claims.

What is claimed is:-

l. The combination of commercial telegraph printers in a radio telegraph system comprising a master transmitter, a plurality of stations, each of said stations comprising a regenerative oscillating detector with an inductive frequency determining circuit, each of the stations being normally tuned to the frequency of the master transmitter, and means at each station operable for transmitting intelligence to all stations in the system, said means comprising an audio fre` quency generator for keying an inductive loop in the oscillating circuit for varying the frequency an audio number of times per second thereof, and electro-mechanical means for producing a single audible note for operating the printer.

2. The combination of commercial telegraph printers in the combination with a radio toning device of a radio telegraph system comprising a master transmitter, a plurality of stations, each of said stations comprising a regenerative oscillating detector with an inductive frequency determining circuit, each of the stations being tuned to the frequency of the master transmitter, and means at each station for transmitting intelligence to all stations in the system, said means comprising an audio frequency generator for keying an inductive loop in the oscillating circuit for varying the frequency an audio number of times per second whereby the audio modulation frequency is separated from all other frequencies so as to enable the conversion of the intelligence impulses into a single audible frequency note, and electro-mechanical means for converting said intelligence impulses into a single audible frequency note.

3. A radio telegraph system comprising a plurality of statipns each of which is initially tuned to the same frequency and comprises a regenerative oscillating detector with an inductive f'requency determining circuit, and a coil coupled to the frequency determining circuit of said detector for varying the frequency of said detector.

4. A radio telegraph system comprising a plurality of stations each of which is initially tuned to the same frequency and comprises a regenerative oscillating detector with an inductive frequency determining circuit, and a coil coupled to the frequency determining circuit of said detector for varying the frequency of said detector, and modulating means in circuit with said coil.

5. A radio telegraph system comprising a plurality of stations each of which is initially tuned to the same frequency and comprises a regenerative oscillating detector with an inductive frequency determining circuit, and a coil coupled to the frequency determining circuit of said detector for varying the frequency of said detector, and modulating means in circuit with said coil, and an audio amplification circuit coupled to the output of said detector.

6. A radio telegraph system comprising a plurality of stations each of which is initially tuned to the same frequency and comprises a regenerative oscillating detector with an inductive frequency determining circuit, and a coil coupled to the frequency determining circuit of said detector for varying tlie frequency of said detector, and an audio frequency generator coupled to said coil, and a key in the coupling.

'7. A radio telegraph system comprising a plurality of stations each of which is initially tuned to the same frequency and comprises a regenera tive oscillating detector with an inductive frequency determining circuit, a coil coupled to the frequency determining circuit of said detector for varying the frequency of said detector, an audio frequency generator coupled to said coil, a key in the coupling, an audio frequency amplication circuit coupled to the output of said detector, and an acoustical filter coupling said audio amplification circuit to a utilization means.

8. A radio telegraph system comprising a plurality of stations each of which is initially tuned to the same frequency and comprises a regenerative oscillating detector with an inductive frequency determining circuit, a coil coupled to the frequency determining circuit of said detector for 5 varying the frequency of said detector, an audio frequency generator coupled to said coil, an audio frequency amplification circuit coupled to the output of said detector, a key in the coupling, automatic typing means, and an acoustical filter coupling said audio amplification circuit to said automatic typing means.

9. A radio telegraph system comprising a plurality of stations each of which is initially tuned to the same frequency and comprises a regenerative oscillating detector with an inductive frequency determining circuit, a coil coupled to the frequency determining circuit of said detector for varying the frequency of said detector, an audio frequency generator coupled to said coil, an audio frequency amplification circuit coupled to the output of said detector, a key in the coupling, automatic typing means, an acoustical lter coupling said audio amplioation circuit to said automatic typing means, said acoustical filter comprising resonance chamlcerA means, electrical means energized by said audio amplification circuit for mechanically producing sound Waves in said resonance chamber means, means connected with said chamber means for modifying said sound waves and releasing from said chamber. means sound Waves of a diierent character, and microphone means operatively connected to automatic typing means and upon which the last mentioned sound Waves operatively impinge.

I WARREN C. HILL. 

